Dual intensity signal lamp

ABSTRACT

A combination dual intensity signal lamp having a constant intensity control filament, a two-position switch actuated by the energization of the control filament to a second position and actuated by the deenergization of the first filament to a first position and a dual intensity signal lamp circuit containing the switch which connects the circuit for a high-intensity mode of operation in the first position and for a low-intensity mode of operation in the second position.

United States Patent Wilson 51 Jan. 25, 1972 [54] DUAL TEN ITY I NAL L Mv 3,349,280 10/1967 Siiberg ..3l5/77 [72] Inventor: Robert Earl Wilson,Las Vegas, Nev. p i E i R ld L, wib n Assistant Examiner-Orville B.Chew, ll [.73] Asslgnee' fil g Watson Las Vegas a pan Attorney-Harris,Kiech, Russell& Kern [22] Filed: Jan. 8, 1970 [57] ABSTRACT [21 Appl.No.: 1,520 A combination dual intensity signal lamp having a constantintensity control filament, a two-position switch actuated by theenergization of the control filament to a second position and 5 3 1actuated by the deenergization of the first filament to a first i q 315/65 67 73 77 position and a dual intensity signal lamp circuitcontaining the l l 0 can: switch which connects the circuit for ahigh-intensity mode of operation in the first position and for alow-intensity mode of [56] References Cned operation in the secondposition.

UN'TEDSTATES PATENTS 10 Claims,'5 Drawing Figures 3,138,737 6/1964French ..315/73 I NVENTOR.

4 HOBERT EARL W/LSON BY Hi6 HTTORNEYS B HARRIS, KIEcH, RUSSELL e2 KERNPATENTEUJANZSIQYZ 3,538,0

snm a or a HOBERT EARL W/LSON BY HIS ATTORNEYS HARE/5, /(/ECH, Aussm 1KERN.

DUAL INTENSITY SIGNAL LAMP This invention relates to a combination dualintensity signal lamp and to a variable intensity vehicle signalingsystem employing the lamp.

More particularly, this invention is directed toward a combination lampwhich canfunction as a rear taillamp, a rear signaling lamp, and a rearemergency brake lamp.

The present motor vehicles in use today are generally equipped withoperating lamps, such as headlamps, parking lamps, taillamps, brakewarning lamps and signaling lamps. In most vehicles, the taillamps serveseveral functions; for example, the rear taillamps are taillamps,signaling lamps, and brake warning lamps.

The combination signaling lamps presently employed on motor vehicles aresingle intensity lamps; that is, the lamps are energized at onebrilliancy. These single intensity lamps create a serious problem inproviding the proper brilliancy for both night and day time drivingconditions. When the lamps are made so as to be sufficiently brilliantto be readily and easily discernible under daytime driving conditions,the lamps are too brilliant for nighttime driving conditions whichcauses an undesirable and hazardous glare which has a tendency todestroy night vision. When the brilliancy of the lamp is compromised soas not to make it objectionable for nighttime driving conditions, thebrilliancy is inadequate for daytime driving conditions, especially onbright sunny days. The conventional method of circumventing thebrilliancy problem has been to make combination tail and signaling lampsof moderate intensity. These lamps, however, are objectionable for theabove reasons.

Workers in the art have also attempted to develop other solutions to theabove problems. One attempted solution has been the development of dualintensity vehicle lamp systems and circuits which provide (1) that thesignal and emergency lamps are of sufficient brightness during daytimedriving conditions so as to be visible and (2) that the lamps are ofreduced brightness during nighttime driving conditions. These systemsand circuits generally employ resistor elements that are switched in andout of the signal lamp circuit to vary the intensity of the signallamps. The switching is performed by custom circuits which embodyspecial or custom headlamp switches or relay switches that arecontrolled by the custom headlamp switches, or photoelectric cells.Although these systems have satisfactorily solved the above brightnessproblem, these systems have not been commercially adapted because theyrequire special circuits and special elements or parts, such as customheadlamp switches, which are expensive and which cannot be readilyinstalled on the present vehicles. A third approach in solving the aboveintensity of brightness problem has been the development of dualintensity lamps for dual intensity vehicle signaling lamp circuits, suchas the lamp and circuit disclosed in US. Pat. No. 3,349,280 which issuedto Hemming G. Siiberg. These dual intensity lamps and circuits havesatisfactorily solved the above brightness problem; however, they stillpresent the same disadvantage seen in the above dual intensity systemsand circuits; that is, the dual intensity lamps and circuits requirespecial circuitry and custom elements which are expensive and cannot bereadily installed on the present vehicles.

. For purposes of the present invention, daytime driving conditions arethose conditions wherein a vehicle is operated without the operation ofheadlamps, and taillamps, and nighttime driving conditions are thoseconditions wherein a vehicle is operated with the operation of headlampsand taillamps, such as during the hours of darkness, during a dark rainyday, during a heavy fog, during a snowstorm, and the like.

It is an object of this invention to provide a combination dualintensity signal lamp which has a high-intensity mode of tensity brakewarning lamp. Even more particularly, it is an object of the presentinvention to provide a dual function dual intensity signal lamp whichoperates at full brilliance during daytime driving conditions and atreduced brilliance during nighttime driving conditions when thetaillamps are on.

It is another object of this invention to provide a dual intensitysignal lamp that can be employed in the signaling circuits of thepresent vehicles to convert the vehicles rear signaling systems from asingle intensity mode of operation to a dual intensity mode of operationwithout requiring modification of the vehicles signaling systems orcircuits. Another and further object of the present invention is toprovide dual intensity signal lamps which will give optimum visualsignals under either daytime driving conditions or nighttime drivingconditions.

The foregoing objects, advantages, features and results of the presentinvention, together with the various other objects, advantages,features, and results thereof which will be evident to those skilled inthe signal lamp art in the light of this disclosure, may be obtainedwith the exemplary embodiments of the invention described in detailhereafter and illustrated in the accompanying drawings.

FIG. I is a schematic illustration of the lamp of the invention in ahigh-intensity mode of operation;

FIG. 2 is a schematic diagram of the lamp of FIG. I in a lowintensitymode of operation;

FIG. 3 is a schematic illustration of an alternate embodiment of thelamp in the high-intensity mode of operation;

FIG. 4 is a schematic diagram of the lamp of FIG. 3 illustrating thelamp in the low-intensity mode of operation; and

FIG. 5 is a schematic diagram of a vehicle operating lamp, signalinglamp, and a brake warning lamp circuit incorporating the dual intensitysignal lamp of FIG. 1.

Referring to the drawings, FIG. 1 shows a lamp 10 having a transparentglass bulb 11 mounted on a lamp base 12 having input terminals 13 and 14and a ground terminal 15. The input terminal 13 is connected by a wire16 to one end of a first or control lamp filament 17, to the other endof which is connected a wire 18 which dead-ends in the base 12. Theinput terminal 14 is connected by a wire 19 to one end of a second orcontrolled lamp filament 20, to the other end of which is connected awire 21 which dead-ends in the base 12. The wire 18 is connected by awire 23 to a first terminal 24 of a switch 25, and the wire 19 isconnected by a wire 26 through a first resistor 27 to a first contact 28of the switch. The wire 21 is connected by a wire 29 to a second contact30 of the switch. The wire 29 is connected by a wire 31 through a secondresistance 32 to wire 33 at connection 34. Wire 33 is connected at oneend to the second terminal 36 of the switch and at the other end to theground terminal 15.

The switch 25 includes the terminals 24 and 36 and a switch arm 39therebetween composed of a pair of metallic strips 41 and 42 bowed apartbut electrically and mechanically joined at their ends. The strip 41being of a metal having a relatively high electrical resistance and ahigh coefficient of expansion. The strip 42 is made of a metal having arelatively low electrical resistance and low coefiicient of expansion.The strips are supported about midway between their ends by theterminals 24 and 36 of which terminal 36 is rigidly supported in thelamp by suitable means (not shown). In the preferred embodiment of theswitch, the strip 42 is prestressed to a second position (FIG. 2) and isbowed to a first position (FIG. I) by the strip 41 when no current isflowing between terminals 24 and 36. Optionally, the strip 41 can beprestressed to the first position (FIG. 1

Theswitch 25 is schematically illustrated in FIG. 1 in'its firstposition in which the switch connects controlled filament 20 for ahigh-intensity mode of operation. When the lamp 10 is energized forsignaling, as when it is installed as a rear taillamp in a vehicle,current from the vehicle's signaling system flows from input terminal 14through wire 19, controlled filament 20, wire 21, wire 29, secondcontact 30, the left end of strip 41, the left leg of strip 42, secondterminal 36, and through wire 33 to output terminal 15. The resistance27 is open circuited at the contact 28 of the switch and the resistance32 is short circuited by the contact 30 and the terminal 36 of theswitch. In this mode of operation the lamp is energized at relativelyhigh brilliancy which is suitable for daytime driving conditions.

Referring to FIG. 2, the switch 25 is schematically illustrated in asecond position in which the switch connects the controlled filament 20for a low-intensity mode of operation. When the lamp is now energizedfor signaling, current flows from input terminal 14 through 19controlled filament 20, wire 21, wire 29, wire 31, second resistor 32,connection 34, and through wire 33 to output terminal 15, and, startingfrom wire 19, through wire 26, first resistor 27, first contact 28, theleft leg of strip 42, second terminal 36, and through wire 33 to theoutput terminal. In the low-intensity mode of operation, the controlledfilament 20 is in parallel with the first resistor 27 and in series withthe second resistor 32. In the low-intensity mode of operation the lampis energized for signaling at relatively low intensity which is suitablefor nighttime driving conditions.

The switch 25 remains in the first position (FIG. 1) as long as thecontrol filament 17 is not energized. When the lamp is energized as ataillamp, the control filament 17 is energized which actuates the switch25 from the first position to the second position (FIG. 2). Morespecifically, current flows from the input terminal 13 through wire 16,control filament 17, wire 18, wire 23, first contact 24, the left andright legs of metallic strip 41, the left and right legs of metallicstrip 42, second contact 36 and through wire 33 to output terminal 15.The current flow through metallic strip 41 produces sufficient heatenergy to cause strip 41 to expand, bow downwardly, disengage the switcharm 39 from the second contact 30, and engage the switch arm with thefirst contact 28. When control filament 17 is deenergized, the switch isactuated to the first position, i.e., current ceases to flow throughmetallic strip 41 which causes the strip to cool, contract, return toits ambient temperature configuration, disengage the switch arm from thefirst contact 28, and engage the switch arm with the second contact 30.

The second resistor 32 is included in the circuit to provide that theimpedance between the input terminal 14 and the ground terminal isfairly constant regardless if the lamp is in the high-intensity orlow-intensity mode of operation.

FIG. 3 and FIG. 4 illustrate another embodiment of the present inventionwith elements corresponding to those of FIG. 1 and FIG. 2 identified bythe same numbers. Referring to FIG. 3, in this embodiment the lamp has atransparent glass bulb 11 mounted on a base 12 having input terminals 13and 14 and a ground terminal 15 substantially identical to those shownin FIG. 1. The lamp has three filaments, a control filament 17 which ismounted and connected as described in FIG. 1, a high-intensity filament44 and a low-intensity filament 45. The input terminal 14 is connectedbya wire 19 to one end of the high-intensity filament 44 and one end ofthe low-intensity filament 45. The other end of the high-intensityfilament is connected to wire 21 which dead-ends in the base 12. Theother end of the low-intensity filament 45 is connected to wire 46 whichdead-ends in the base 12. The wire 21 is connected by wire 29 to thesecond contact 30 of the switch 25. The wire 46 is connected by wire 47to the first contact 28 of the switch 25. The switch 25 is mounted andconnected as described in FIG. 1.

In the high-intensity mode of operation (FIG. 3) the control filament 17is off, i.e., not energized, the switch 25 is in the first position, andthe high-intensity filament 44 is energized, such as for signaling, asfollows: current flows from the input terminal 44, through wire 19, thehigh-intensity filament 44, wire 21, wire 29, second contact 30, theleft end of metallic strip 41, the left leg of metallic strip 42, secondterminal 36 through wire 33 to the ground terminal 15.

In the low-intensity mode of operation (FIG. 4) the control filament 17is energized, as described in FIG. 2, which actuates the switch 25 tothe second position, as described in FIG. 2, and the low-intensityfilament 45 is energized as follows: current flows from input terminal14 through wire 19, the lowintensity filament, wire 46, wire 47, contact28, the left leg of metallic strip 42, terminal 36 and through wire 33to the ground terminal 15.

The filaments 44 and 45 are equal in impedance and equal wattagefilaments, where the filament 45 is either electrically or opticallyinefficient. In another embodiment of the invention (not shown) thefilament 44 has ahigher wattage and impedance than filament 45. In suchembodiment a resistor (not shown) is electrically included in thecircuit between the filament 45 and the first contact 28 to provide thatthe impedance between the input terminal 14 and the ground terminal isfairly constant regardless of what mode of operation the lamp Althoughthe present invention has been described with switch 25, the inventionis not limited to this switch. The present lamp can employ atwo-position bimetallic switch which is actuated by the energization anddeenergization of the control filament 17, a two-position relay orsolenoid switch which is actuated by the energization and deenergizationof the control filament, and the like.

Although not illustrated, a shunt lead can be connected from the outputof the control filament 17 to the ground terminal 15 to reduce thecurrent load across the switch 25. However, this generally will not benecessary for low-wattage lamps, such as motor vehicle taillamps.

FIG. 5 illustrates a conventional vehicle-lighting system consisting ofoperating lamps, emergency brake lamps and signal lamps. The operatinglamps consist of the headlamps (not shown), the front parking lamps, andthe rear taillamps. The left front parking lamp and left front turnsignal lamp are combined into one lamp 49a; similarly, the right frontparking lamp and the right front turn signal lamp are combined into asignal lamp 49b. The left taillamp, the left rear brake warning lamp andthe left rear turn signal lamp are combined into one lamp 10a; similarlythe right taillamp, the right rear brake warning lamp, and the rearright turn signal lamp are combined into a signal lamp 10b. Lamps 10aand 10b are of the same construction and design as lamp 10 which isillustrated in FIGS. 1 and 2.

FIG. 5 shows a battery 50 connected by a wire 51 through an ignitionswitch 52 to one end of a flasher element 53, the other end of which isconnected to wire 54. The wire 51 is connected by a wire 55 through ahazard light flasher element 56 to one end of a hazard light switch 57,the other end of which is connected to wires 58, 59 and 60. The wire 55is connected by wire 61 to one end of the emergency brake light switch62, the other end of which is connected to wire 63. The wire 54 isconnected through connection 66 to a left terminal 67 of a signal switch68. The connection 66 is connected by wire 69 to a right terminal 70 ofthe switch 68. The wire 58 is connected to a common terminal 71. Thewires 59 and 60 are connected to wires 72 and 73, respectively. The wire63 is connected to wire 58 at connection 74. The wire 72 connects a leftfront contact 76 of the switch 68 with an input terminal 770 of a leftfront parking and signaling lamp 49 a. The wire 73 connects a rightfront contact 79 of the switch 68 with an input terminal 77b of a rightfront parking and signaling lamp 49b. The wire 72 is connected by wire82 with one end of a left turn indicator lamp 83, the other end of whichis connected to a ground contact 84. The wire 73 is connected by wire 85with one end of a right turn indicator lamp 86, the other end of whichis grounded to the terminal 84.

The switch 68 has a contact bar 88 which is engaged with the terminal71, a left contact 89 and a right contact 90. The switch 68 also has adisengaged left contact bar 91 and a disengaged right contact bar 92.The left contact 89 is connected by wire 94 to an input terminal 140 ofthe left taillamp 10a. The right contact is connected by wire 95 to aninput terminal 14b of the right taillamp 10b. The switch 68 is actuatedby a hand lever (not shown) which upon the appropriate movement movesthe contact bar 88, the left contact bar 91 and the right contact bar 92to engage and disengage certain contacts and terminals as describedbelow.

The battery 50 is also connected by wire 51 to an input terminal 96 of aheadlamp switch 97. The input terminal 96 is connected by a slidecontact 98 to a contact bar 99. The switch 97 has two taillamp contacts101 and 102 which are connected to wire 103. The switch also has aparking lamp contact 104 which is connected to wire 105 and a headlampcontact 106 which is connected to wire 107. The wire 103 is connected tothe input terminal of a license plate lamp (not shown) and inputterminals 13a and 13b of the left and right taillamps a and 10b,respectively. The wire 105 is connected to input terminals 108a and l08bof the left and right front parking lamps, 49a and 4%, respectively. Thewire 107 is connected to one end of a high-low beam headlamp switch (notshown), the other end of which is connected to the headlamps (notshown).

The left and right taillamps 10a and 10b have ground terminals a and15b, respectively, which are connected by wire 109 to a rear groundcontact 110.

The left and right front parking lamps 49a and 49b are of the standardtype. The input terminal 77a of the left lamp 49a are connected by wire111a to one end of a signal light filament 112a, the other end of whichis connected to a ground terminal 113a. Similarly, the input terminal77b of the right lamp 49b is connected by wire lllb to one end of asignal light filament 112b, the other end of which is connected to aground terminal 1l3b. The input terminal 10811 of the left lamp 49b isconnected by wire 114a to one end of a parking light filament 115a, theother end of which is connected to the terminal 113a. Similarly theinput terminal 108b of the right lamp 49b is connected by wire 11411 toone end of a parking light filament 115b, the other end of which isconnected to the terminal 1l3b The ground terminals 113a and 1l3b areconnected by wire 1 16 to a front ground contact 117. The operation ofthe above-described vehicle lamp and signal circuit will now bedescribed employing the dual intensity lamps of this invention.

DAYLIGI-IT OPERATION During daylight operation, the respective switchesare engaged as shown in FIG. 5. When the brakes are applied, resultingin closure of brake warning switch 62, the left and right taillamps 10aand 1012, respectively, will be energized over the following circuit:from the positive terminal of the vehicle battery 50 through wire 51,wire 55, wire 61,'switch 62, wire 63, connection 74, common terminal 71,contact bar88, left contact 89, wire 94, input terminal 14a, through theleft taillamp 10a over the circuit shown in FIG. 1, ground terminal 15a,and through wire 109 to the rear ground contact 110, and from .contactbar 88, through the right contact 90, wire 95, input terminal 14b,through the right taillamp 10b over the circuit shown in FIG. 1, groundterminal 15b, and through wire 109 to the rear ground contact 110. Inthis mode, the taillamps are ,operated as brake warning lamps at fullbrilliancy; i.e., the

lamps are operated in the high-intensity mode.

To signal a left turn, the directional signal switch 68 is appropriatelyactuated by movement of a hand lever which disengages the contact bar 88from the right contact 90 and the common contact 71 and engages it withthe left terminal 67 the left front contact 76 and the left contact 89and engages the right contact bar 92 with the right terminal 70, thecommon tenninal 71, and the right contact 90. The left contact bar 91remains disengaged. The left taillamp 10a is now energized over thefollowing circuit: from the positive terminal of the battery 50 throughwire 51, switch 52, flasher element 53, wire 54, connection 66, leftterminal 67, contact bar 88, left contact 89, wire 94, input terminal14a, through the left taillamp over the circuit shown in FIG. 1, throughground terminal 15a, and through wire 109 to the rear ground contact110. In this mode, the left taillamp 10a is energized at fullbrilliancy; i.e., the controlled filament 20 of the lamp 10a is operatedin the high-intensity mode. Also, when starting from the contact bar 88,the front parking lamp 49a is energized over the following circuit:through the left front contact 76, wire 72, input terminal 77a, wire111a, filament 112a, ground terminal 113a, and through wire 116 to thefront ground contact 117. Likewise, starting from left front contact 76,the left turn indicator lamp 83 is energized through wire 72, wire 82,and through the lamp83 to the ground contact 84.

To signal a right turn, the directional signal switch is appropriatelyactuated by movement of a hand lever which disengages the right contactbar 92 from the right terminal 70, the common terminal 71 and the rightcontact 90, disengages the contact bar 88 from the left terminal 67 andthe contacts 76 and 89, and engages it with the right terminal 70, theright front contact 79 and the right contact 90; and engages the leftcontact bar 91 with the left terminal 67, the common tenninal 71 and theleft contact 89. Commencing from flasher element 53, the right taillamp106 is energized over the following circuit: from the flasher element 64through wire 54, connection 66, wire 69, right terminal 70, the contactbar 88, right contact 90, wire 95, input terminal 1411, through theright taillamp "over the circuit shown in FIG. 1 through the groundterminal 15b, and through wire 109 to the rear ground contact 110. Also,in starting from the contact bar 88, the right parking lamp is energizedover the following circuit: through the right front contact 79, wire 73,input terminal 77b, wire 111b, filament 112b, ground terminal 113a, andthrough wire 116 to the front ground contact 117. Likewise, and startingfrom the right front contact 79, the right turn indicator lamp 86 isenergized over the following circuit: through wire 73, wire and throughthe right turn indicator lamp 86 to the ground contact 84. In this modeof operation, the right taillamp 10b is energized at full brilliancy.

When signaling a right turn, if the brakes are applied resulting in theclosure of the brake switch 62, the right taillamp is energized forflashing signaling as described above and the left taillamp is energizedfor brake warning as described above. The right taillamp is notenergized for braking because the common terminal 71 and the rightcontact of the switch 68 are not electrically connected when the switchis actuated for signaling a right turn. The reverse situation existswhen the brakes are applied during the signaling of a left tum, i.e.,the right taillamp 10b is energized for brake warning and the lefttaillamp 10a is energized for signaling.

When the hazard light switch 57 is closed, the directional signal switch68 is in the position shown in FIG. 5 and the two taillamps and the twoparking lamps will be concurrently energized. The left taillamp 10a isenergized over the following circuit: from the positive terminal of thevehicle battery 50 through wire 51, wire 55, flashing element 56, hazardlight switch 57, wire 58, common terminal 71, contact bar 88, leftcontact 89, wire 94, input terminal 14a, through the left taillamp 10aover the circuit shown in FIG. 1, through the ground terminal 15a, andthrough wire 109 to the rear ground contact 110. Similarly, from contactbar 88 the right taillamp is energized as follows: from the rightcontact 90, through wire 95, input terminal 14b, through the righttaillamp 10b over the circuit shown in FIG. 1, through ground terminal15b, and through wire 109 to the rear ground contact 110. Also, whenstarting from the hazard light switch 57, the left parking lamp 49a isenergized over the following circuit: from the hazard light switch 57through wire 59, wire 72., input terminal 77a and through the leftparking lamp to the front ground contact as described above. The rightparking lamp 49b is energized from the switch 57, through wire 60, wire73, input terminal 77b and through the right parking lamp 49b to thefront ground terminal 117 as described above.

OPERATION UNDER NIGI-ITTIME CONDITIONS During operation of vehiclesunder nighttime driving conditions, the contact bar 99 of the headlampswitch 97 is moved by the actuation of a hand lever (not shown) toengage the slide contact 98, the taillamp contact 102 and the headlampcontact 106. The taillamps are energized over the following circuit:from the positive terminal of the battery 50 through wire 51, inputterminal 96, slide contact 98, contact bar 99, taillamp contact 102,wire 103, input terminals 13a and 13b of the taillamps a and 10b,respectively, through the left and right taillamps 10a and 1012 over thecircuit shown in FIG. 2, through the ground terminals a and 15b, andthrough wire 109 to the rear ground contact 110. Starting from contactbar 99, the headlamps are energized through headlamp contact 106, wire107 and through the high-low beam switch to the various headlamps (notshown). During nighttime driving conditions, when the brakes areapplied, the rear taillamps 10a and 10b are energized as far as inputterminals 14a and 14b, respectively, over the same vehicle-brakingcircuit described above for daytime driving conditions. From inputterminal 14a of the left taillamp, the lamp is energized over thecircuit shown in FIG. 2 to the ground terminal 15a and through a wire109 to the rear ground contact 110. Similarly, from the input terminal14b of the right taillamp 10b, the lamp is energized over the circuitshown in FIG. 2 to the ground terminal 15b. Accordingly, when the brakesare applied, the two rear taillamps 10a and 10b are not energized atfull brilliancy; i.e., the rear lamps are energized in theirlow-intensity mode of operation which is suitable for nighttime drivingconditions.

When a left turn is to be indicated by signaling through the signallamps, up to input terminal 14a, the left taillamp is energized overvehicle signal circuit described above for a left turn under daytimedriving conditions. From input terminal 14a to the ground terminal 15aof the left taillamp 10a, the lamp is energized over the circuit shownin FIG. 2. The left taillamp 10a is now energized for signaling at areduced brilliancy in relation to the daylight operation signalbrilliancy. The left front or the left parking lamp 49a is energizedover the circuit described above for left turn signaling under daytimedriving conditions.

When a right turn is to be indicated by signaling through a signal lamp,up to the input terminal 14b, the right taillamp 10b is energized overthe vehicle signal circuit described above for a right turn underdaytime driving conditions. Through the right taillamp 10b from theinput terminal 14b and the ground terminal 15b, the lamp is energizedover the circuit shown in FIG. 2. From the ground terminal 15b thecurrent flows through wire 109 to the rear ground contact 110. There isno change in operation for the energization of the right parking lamp49b for signaling, and it is energized over the circuit described abovefor a right turn under daytime driving conditions. When signaling aright turn, if the brakes are applied resulting in the closure of brakeswitch 62, the right taillamp 10a is energized for signaling asdescribed immediately above and the left taillamp 10a is energized forbrake warning over the circuit described above for braking undernighttime driving conditions.

When the hazard light switch 57 is closed, the two taillamps 10a and 10bup to input terminals 14a and 14b are concurrently energized over thesame circuit described for hazard lamp operation under daytime drivingconditions. However, between input terminal 14a and ground terminal 15aof the left taillamp 10a and the input terminal 14b and the groundterminal 15b of the right taillamp 10b, the lamps are energized over thecircuit shown in FIG. 2. From the ground terminals 150 and 15b thecurrent flows through wire 109 to the rear ground contact 110. Since thecontrol filaments 17 of the rear taillamps are energized, these lamps10a and 10b will be energized at a reduced brilliancy for hazard lightoperation. Since there is no change of operation for the left and frontparking lamps 49a and 49b for hazard light signaling, these lamps areenergized over the circuit described for hazard light operation underdaytime driving conditions.

When the headlamp switch is placed on off position, i.e., the positionillustrated in FIG. 5, the control filaments 17 of the left and rightrear taillamps 10a and 10b are deenergized causing the lamps to revertto the high-intensity mode of operation described above. Although notshown in FIG. 5, some vehicle lighting systems provide for theenergization of the parking lamps with the headlamps; such a conditionwould exist if wire was connected to wire 103 instead of parking lampcontact 104 of the headlamp switch 97. In such systems, the presentlamps (FIGS. 1 and 2, or FIGS. 3 and 4) can be installed in the parkinglamp sockets to convert the parking lamps to dual intensity lamps. Forexample, assuming the headlamp switch 97 was just as describedimmediately above, the lamp 10, as shown in FIG. 1, could be installedin place of the left parking lamp 49a where input terminal 13 wouldreplace input terminal 108a and input terminal 14 would replace inputterminal 77 and ground terminal ,15 would replace ground terminal 113a.In such a situation, when the parking lamp is not energized as a parkinglight, i.e., when the control filament 17 is not energized (FIG. I), theparking lamp will operate in the high-intensity mode. When the parkinglamp is energized as a parking light, i.e., when the control filament 17is energized (FIG. 2), the front parking lamp will operate in thelow-intensity mode.

Although the circuit of FIG. 5 has been described employing the dualintensity signal lamp of FIGS. 1 and 2, the circuit is not limited tothat embodiment of the invention. The dual intensity signal lamp ofFIGS. 3 and 4 can also be employed in the above circuit to achieve thesame results without requiring any modification of the circuit.

From the foregoing, it is readily apparent that the dual intensity lampof the present invention can be employed in the taillamp-rear signallamp circuits of the present vehicles without modification of theircircuits to convert their signaling lamp systems, brake warning lampsystems and hazard lamp 7 systems from a single intensity mode ofoperation to a dual intensity mode of operation.

Iclaim:

l. A dual intensity lamp, including:

a base adapted to be inserted in a lamp socket;

a transparent lamp envelope mounted on said base;

first and second filaments separately mounted in said envelope, saidfilaments both being adapted to be electrically energized when said baseis in such a socket;

a means for reducing electrical current passing through said secondfilament when an electrical current of predetermined load is passedthrough said first filament comprising a two-position switch meansmounted in said lamp envelope and electrically connected to said firstfilament, said switch means being actuated from a first position to asecond position upon the electrical energization of said first filamentand actuated back to said first position upon the deenergization of saidfirst filament; and a first resistor mounted in said envelope, saidswitch means in said first position electrically connecting said secondfilament for the passage of electrical current of a predetermined loadfor high-intensity operation, said switch means in said second positionelectrically connecting said second filament in parallel with saidresistor for reducing the electrical current passing through said secondfilament for low-intensity operation.

2. The dual intensity lamp as defined in claim 1 wherein said baseincludes external first and second base terminals and a ground terminal;

said two-position switch means includes first and second metallic stripselectrically connected together at their ends and bowed apart betweensuch ends, said first strip having a relatively high electricalresistance and coefficient of expansion and said second strip having arelatively low resistance and coefficient of expansion, first and secondswitch terminals and first and second contacts, said first terminalbeing electrically connected to said first strip and said secondterminal being electrically connected to said second strip;

means for electrically connecting one end of said first filament to saidfirst base terminal and the other end of said first filament to saidfirst switch terminal;

means for electrically connecting one end of said second filament tosaid second base terminal and the other end of said second filament tosaid first switch contact; means for electrically connecting one end ofsaid resistor to said second base terminal and the other end of saidresistor to said second switch contact; and 1 means for electricallyconnecting said second switch terminal to said ground terminal.

3. The dual intensity lamp as defined in claim 2 including means forelectrically connecting said first switch contact through a secondresistor to said base ground terminal to provide a substantially equalimpedance between said second base terminal and said ground terminal.

4. The dual intensity lamp as defined in claim 1 including a secondresistor mounted in said envelope, said switch means in the firstposition electrically shorting out said second resistor, said switchmeans in the second position electrically connecting said secondresistor in series with said second filament.

5. A dual intensity lamp, including:

a base adapted to be inserted in a lamp socket; v

a transparent lamp envelope mounted on said base;

first, second and third filaments separately mounted in said envelope,said filaments being adapted to be electrically energized when said baseis in such a socket, said second filament energized at a relatively highintensity, said third filament energized at a relatively low intensity;and

means for switching the electrical current passing through said secondfilament to said third filament when an electrical current ofpredetermined intensity is passed through said first filament, andswitching back the electrical current passing through said thirdfilament to said second filament when said first filament iselectrically deenergized.

6. A dual intensity lamp as defined in claim 5 wherein the means forswitching the electrical current comprises a twoposition switch meansmounted in said lamp envelope and electrically connected to said firstfilament, said switch means being actuated from a first position to asecond position upon the energization of said first filament andactuated back to said first position upon the deenergization of saidfirst filament, said switch means in said first position electricallyconnecting said second filament for the passage of electrical current,and said switch means in said second position electrically connectingsaid third filament for the passage of electrical current.

7. The dual intensity lamp as defined in claim 6 wherein said second andthird filaments are equal impedance and equal wattage filaments.

8. The dual intensitylamp as defined in claim 6 including a resistorconnected in series with said third filament, the impedance of saidresistor and said third filament in series being about equal to theimpedance of said second filament.

9. The dual intensity lamp as defined in claim 6 wherein said baseincludes external first and second base terminals and a ground terminal;

said two-position switch means includes first and second switchterminals, first and second contacts, and first and second metallicstrips electrically and mechanically connected together at their endsand bowed'apart between such ends, said first strip having a relativelyhigh electrical resistance and coefficient of expansion and said secondstrip having a relatively low resistance and coeffi cient of expansion,said first terminal being electrically connected to said first strip andsaid second terminal being electrically connected to said second strip;

means for electrically connecting one end of said first filament to saidfirst base terminal and the other end of said first filament to saidfirst switch terminal;

means for electrically connecting one end of said second filament tosaid second base terminal and the other end of said second filament tosaid first switch contact;

means for electrically connecting one end of said third filament to saidsecond base terminal and the other end of said third filament to saidsecond switch contact; and means for electrically connecting said secondswitch terminal to said ground terminal.

20. A dual intensity lamp including:

a base having external first and second base terminals and a groundterminal; I

a transparent lamp envelope mounted on said base;

a control filament in said envelope;

a controlled filament in said envelope;

a switch in said envelope having first and second switch terminals andfirst and second contacts, said switch including a pair of metallicstrips electrically connected together at their ends and bowed apartbetween such ends, one of said strips having a relatively highelectrical resistance and coefficient of expansion and the other of saidstrips having a relatively low resistance and coefficient of expansion,one of said terminals being electrically connected to one of said stripsand the other terminal being electrically connected to the other of saidstrips;

means electrically connecting one end of said control filament to saidfirst base terminal and the other end of said control filament to saidfirst switch terminal;

means for electrically connecting one end of said controlled filament tosaid second base terminal and through a first resistor to second switchcontact and the other end of said controlled filament to said firstswitch contact and, through a second resistor, to said ground terminal;and

means for electrically connecting said ground terminal to said secondswitch terminal.

1. A dual intensity lamp, including: a base adapted to be inserted in alamp socket; a transparent lamp envelope mounted on said base; first andsecond filaments separately mounted in said envelope, said filamentsboth being adapted to be electrically energized when said base is insuch a socket; a means for reducing electrical current passing throughsaid second filament when an electrical current of predetermined load ispassed through said first filament comprising a twoposition switch meansmounted in said lamp envelope and electrically connected to said firstfilament, said switch means being actuated from a first position to asecond position upon the electrical energization of said first filamentand actuated back to said first position upon the deenergization of saidfirst filament; and a first resistor mounted in said envelope, saidswitch means in said first position electrically connecting said secondfilament for the passage of electrical current of a predetermined loadfor high-intensity operation, said switch means in said second positionelectrically connecting said second filament in parallel with saidresistor for reducing the electrical current passing through said secondfilament for low-intensity operation.
 2. The dual intensity lamp asdefined in claim 1 wherein said base includes external first and secondbase terminals and a ground terminal; said two-position switch meansincludes first and second metallic strips electrically connectedtogether at their ends and bowed apart between such ends, said firststrip having a relatively high electrical resistance and coefficient ofexpansion and said second strip having a relatively low resistance andcoefficient of expansion, first and second switch terminals and firstand second contacts, said first terminal being electrically connected tosaid first strip and said second terminal being electrically connectedto said second strip; means for electrically connecting one end of saidfirst filament to said first base terminal and the other end of saidfirst filament to said first switch terminal; means for electricallyconnecting one end of said second filament to said second base terminaland the other end of said second filament to said first switch contact;means for electrically connecting one end of said resistor to saidsecond base terminal and the other end of said resistor to said secondswitch contact; and means for electrically connecting said second switchterminal to said ground terminal.
 3. The dual intensity lamp as definedin claim 2 including means for electrically connecting said first switchcontact through a second resistor to said base ground terminal toprovide a substantially equal impedance between said second baseterminal and said ground terminal.
 4. The dual intensity lamp as definedin claim 1 including a second resistor mounted in said envelope, saidswitch means in the first position electrically shorting out said secondresistor, said switch means in the second position electricallyconnecting said second resistor in series with said second filament. 5.A dual intensity lamp, including: a base adapted to be inserted in alamp socket; a transparent lamp envelope mounted on said base; first,second and third filaments separately mounted in said envelope, saidfilaments being adapted to be electrically energized when said base isin such a socket, said second filament energized at a relatively highintensity, said third filament energized at a relatively low intensity;and means for switching the electrical current passing through saidsecond filament to said third filament when an electrical current ofpredetermined intensity is passed through said first filament, andswitching back the electrical current passing through said thirdfilament to said second filament when said first filament iselectrically deenergized.
 6. A dual intensity lamp as defined in claim 5wherein the means for switching the electrical current comprises atwo-position switch means mounted in said lamp envelope and electricallyconnected to said first filament, said switch means being actuated froma first position to a second position upon the energization of saidfirst filament and actuated back to said first position upon thedeenergization of said first filament, said switch means in said firstposition electrically connecting said second filament for the passage ofelectrical current, and said switch means in said second positionelectrically connecting said third filament for the passage ofelectrical current.
 7. The dual intensity lamp as defined in claim 6wherein said second and third filaments are equal impedance and equalwattage filaments.
 8. The dual intensity lamp as defined in claim 6including a resistor connected in series with said third filament, theimpedance of said resistor and said third filament in series being aboutequal to the impedance of said second filament.
 9. The dual intensitylamp as defined in claim 6 wherein said base includes external first andsecond base terminals and a ground terminal; said two-position switchmeans includes first and second switch terminals, first and secondcontacts, and first and second metallic strips electrically andmechanically connected together at their ends and bowed apart betweensuch ends, said first strip having a relatively high electricalresistance and coefficient of expansion and said second strip having arelatively low resistance and coefficient of expansion, said firstterminal being electrically connected to said first strip and saidsecond terminal being electrically connected to said second strip; meansfor electrically connecting one end of said first filament to said firstbase terminal and the other end of said first filament to said firstswitch terminal; means for electrically connecting one end of saidsecond filament to said second base terminal and the other end of saidsecond filament to said first switch contact; means for electricallyconnecting one end of said third filament to said second base terminaland the other end of said third filament to said second switch contact;and means for electrically connecting said second switch terminal tosaid ground terminal.
 20. A dual intensity lamp including: a base havingexternal first and second base terminals and a ground terminal; atransparent lamp envelope mounted on said base; a control filament insaid envelope; a controlled filament in said envelope; a switch in saidenvelope having first and second switch terminals and first and secondcontacts, said switch including a pair of metallic strips electricallyconnected together at their ends and bowed apart between such ends, oneof said strips having a relatively high electrical resistance andcoefficient of expansion and the other of said strips having arelatively low resistance and coefficient of expansion, one of saidterminals being electrically connected to one of said strips and theother terminal being electrically connected to the other of said strips;means electrically connecting one end of said control filament to saidfirst base terminal and the other end of said control filament to saidfirst switch terminal; means for electrically connecting one end of saidcontrolled filament to said second base terminal and through a firstresistor to second switch contact and the other end of said controlledfilament to said first switch contact and, through a second resistor, tosaid ground terminal; and means for electrically connecting said groundterminal to said second switch terminal.